The present invention relates to a diagnostic system for detecting a failure of a seat belt retractor installed in a vehicle or an automobile. More particularly, the present invention relates to a failure diagnostic system for a seat belt retractor having a motor for rotating a spool around which webbing is wound.
As well known in the art, a seat belt retractor includes a webbing to be unwound to extend along an occupant sitting on a vehicle seat. In case of a vehicle collision, the seat belt retractor locks the webbing from being unwound so as to restrain the occupant.
Among such seat belt retractors, a motorized seat belt retractor has a motor for rotating a webbing take-up spool. There are various types of motorized seat belt retractors, such as a type in which a motor unwinds and winds the webbing and a type in which a motor works only for a pre-tensioning operation (operation of winding a slack of the webbing upon a collision or collision prediction). It should be noted that the present invention could be applied to any type of seat belt retractors.
It is an object of the present invention to provide a failure diagnostic system for the seat belt retractor for reliably detecting a failure of a motor in the seat belt retractor while the occupant feels no or little discomfort.
Further objects and advantages of the invention will be apparent from the following disclosure of the invention.